The present invention relates to a plasma display panel (PDP), and more particularly to a driving electrode structure having a driving electrode that improves the driving characteristic of the luminant cell.
Since the field of multimedia applications is developing quickly, the user has a great demand for entertainment equipment. Conventionally, the cathode ray tube (CRT) display, a type of monitor, is commonly used. However, the cathode ray tube display does not meet the needs of multimedia technology because it has a large volume. Therefore, many flat panel display techniques such as liquid crystal display (LCD), plasma display panel (PDP), and field emission display (FED) have been recently developed. These display techniques can manufacture a thin, light, short and small monitor, and thus these techniques are going to be the mainstream technology for the future. In these techniques, the plasma display panel (PDP) is attracting attention in the field of displays as a full-color display apparatus having a large size display area and is especially popularly utilized in large-size televisions or outdoor display panels. This is because of its capability of a high quality display resulting from the fact that it is of a self-light emitting type with a wide angle of visibility and high speed of response as well as being suited to upsizing due to a simple manufacturing process.
A color PDP is a display in which ultraviolet rays are produced by gas discharge to excite phosphorus so that visible lights are emitted therefrom to perform a display operation. Depending upon a discharge mode, the color PDP is classified as an alternating current (AC) or a direct current (DC) type. In the AC-type PDP, an electrode is covered with a protective layer. The AC-type PDP has such characteristics that it inherently has a long life and a high brightness. Therefore, the AC-type PDP is generally superior to the DC-type PDP in luminance, luminous efficiency and lifetime. Generally, a 3-electrode type PDP including a common electrode, a scan electrode and an address electrode is employed in the AC-type PDP. The 3-electrode type is directed to a surface discharge type and is switched or sustained based on a voltage applied to the address electrode installed at a lateral surface of a discharge cell.
FIG. 1 is a schematic plan view of a conventional plasma display panel in accordance with the prior art. Several pairs of conductive electrodes 10 are parallel arranged, and each pair of the conductive electrodes 10, including a common electrode and a scan electrode, is symmetrically disposed. A plurality of parallel barrier ribs 20 is disposed with a direction perpendicular to the conductive electrodes 10. By the arrangement of the conductive electrodes 10 and barrier ribs 20, a plurality of luminant cells 30 is array scaled therein.
The common and scan electrodes formed on an image display side substrate are generally formed of a transparent electrode 14 made of a glass material for implementing a certain transmittivity of visual ray. A non-transparent electrode 12 having a small width, generally referred as a bus electrode, is used integrally with respect to the transparent electrode 14. The transparent electrode material is a semiconductor typically formed of ITO (e.g., a mixture of indium oxide In2O3 and tin oxide SnO2). The conductivity of the transparent electrode 14 is low in comparison with that of metal and therefore a narrow width and fine conductive layer is added as the bus electrode on the transparent electrode 14 to enhance its conductivity.
When an address discharge voltage is supplied to the scan electrode and a corresponding address electrode between the barrier ribs 20 (not shown), an address discharge is generated between the scan electrode and the address electrode. An electric field is formed in the interior of a corresponding luminant cell 30, the electrons of the discharge gases are accelerated, and the accelerated electrons collide with ions. At this time, the ionized electrons collide with neutral particles, so that the neutral particles are ionized into electrons and ions at high speed, whereby discharge gas becomes a plasma state, and a vacuum ultraviolet ray is formed.
In a color plasma display panel, ultraviolet rays are converted into light of three primary colors, such as red (R), green (G) and blue (B), by fluorescent layers coated on an inner wall of each luminant cell 30. In order to attain color light emission display, it is important to obtain good white balance characteristic determined by the balance of luminance of the respective three primary colors. In a conventional plasma display, color temperature of white color obtained by simultaneously applying retaining pulses to a red cell, a green cell and a blue cell is approximately about 6500-7500 degrees Kelvin, and is not high enough. With respect to the white balance of this case, white color deviation is approximately 0.01 to 0.015 uv, and especially deviates toward a green color. This is because the dielectric constants of red, green and blue fluorescent substances are different, such that the green fluorescent substance is hard to be driven. In the NTSC system, a higher temperature of 9300 degrees Kelvin is used as a reference white color, as well as a high color temperature is preferred to a low color temperature because of vividness of white color. However, when the color temperature is adjusted to 9300 degrees Kelvin under low color deviation, the number of intensity level of green color will be greatly decreased, even to lower than 200 steps, so that results in a problem of insufficient intensity level numbers.
One way to solve this problem is to change the size of the discharge cells so that intensity of light emission of each color is correspondingly changed, as shown in Japanese patent laid-open publication No. 7-226945. In such an example, when the plasma display panel is driven to display an image, a driving margin to perform a good display as a whole panel decreases.
It is an object of the present invention to provide a driving electrode structure of a plasma display panel in which a driving electrode is disposed in a hard-driven primary luminant cell such as a green luminant cell to improve the driving characteristic thereof.
It is another object of the present invention to provide a driving electrode structure of a plasma display panel in which display of image produced at high color temperature can be obtained without deterioration of luminous efficiency and drive characteristic.
It is a further object of the present invention to provide a driving electrode structure of a plasma display panel in which the brightness of green color can be depressed by the driving electrode structure so that white color can be balanced with small white color deviation.
It is a yet object of the present invention to provide a driving electrode structure of a plasma display panel in which the number of intensity level of green color can be preserved even at high color temperature with small white color deviation.
In one aspect, the present invention provides a driving electrode structure for a plasma display panel formed on a transparent electrode across a plurality of ruminant cells in row. The structure comprises a main electrode located on one side of the transparent electrode adjacent to the edge of the luminant cells, and a driving electrode located in at least one luminant cell and separated by a distance from the main electrode. The driving electrode has two branches by which the driving electrode is connected to the main electrode.
In another aspect, the present invention provides a driving electrode structure for a plasma display panel formed on a transparent electrode across a plurality of pixels in a row of which each pixel is composed of at least three luminant cells. The structure comprises a driving electrode and a side electrode. The driving electrode is located in one ruminant cell of each pixel and separated by a distance from the side of the transparent electrode adjacent to the edge of the ruminant cells. The driving electrode has two branches coupled to two ends of the driving electrode. The side electrode is located in other luminant cells of each pixel and on the side of the transparent electrode adjacent to the ruminant cells. The side electrode connects the branches in adjacent pixels.
The driving electrode is preferably located in green ruminant cells that are hard to be driven such that the driving characteristic of green ruminant cells can be improved.